Nonlinear Dynamical Analysis for an Ethanol Steam Reformer: A Singular Distributed Parameter System

This article provides a theoretical analysis of the nonlinear dynamics of an ethanol steam reformer, which has the potential to become a key technology for the creation of a hydrogen economy. A set of nonlinear partial differential equations is analyzed that arise from material and energy balances for an ethanol steam reformer. Although all of the governing equations contain derivatives with respect to both space and time, the nonlinear distributed parameter system is shown to be singular by structural rank analysis. A numerical method is proposed for simulation of the singular dynamical system. The character of the singularity is analyzed for both the distributed parameter systems and the lumped parameter system used in its simulation. The nonlinear spatiotemporal and input-output behavior of the system are analyzed, including by calculation of a nonlinearity measure applicable to singular distributed parameter systems. Although some states are highly nonlinear functions of the control inputs, a linear low-order input-output model with uncertainty description is shown to be suitable for controller design.